Supervisory Control and Data Acquisition (SCADA) systems have been in operation for many years now and they are widely used for monitoring and/or controlling various remote subsystems. For example, SCADA based solutions are deployed in various power grids, gas pipelines, and railway systems throughout the globe today. Through the use of SCADA systems operators can read data, such as actual resource usage or flow, from individual subsystems and/or can control the subsystem, for example to open or shut a gas pipeline. A communication network is therefore required between the remote SCADA subsystems and the main node, which is also referred to herein as a master node. Legacy, time division based communication networks are already in place to provide the required connectivity between the master node and the subsystems. However, many of these networks are slowly reaching their useful life and many vendors of the equipment used in these networks are terminating support for their legacy equipment. Operating such aging gear is also becoming difficult as equipment vendors are not manufacturing such legacy equipment anymore.
Another issue is the requirement to introduce new services like Voice over Internet Protocol (VoIP), video surveillance, and so on into SCADA systems. Given the age of the legacy networks providing connectivity in many SCADA solutions, the network nodes typically do not have the capacity for additional bandwidth demanding applications. Migrating to a modern Internet Protocol (IP)/Multi-protocol Label Switching (MPLS) based solution while preserving investments made in existing TDM-based non-IP SCADA equipment is a key challenge. SCADA systems typically make use of a point-to-multipoint (P2MP) and multipoint-to-point (MP2P) transmission provided via multi-drop data bridge/bus (MDDB) configurations. While such transmission can be provided for asynchronous traffic by existing IP/MPLS capabilities, providing such transmission for TDM traffic over IP/MPLS is currently undefined. At present, carrying TDM traffic over an IP/MPLS network operates solely in a point-to-point manner. However, for SCADA systems with dozens or even hundreds of subsystems providing such point-to-point connections over an IP/MPLS network becomes cumbersome to manage and an inefficient use of network bandwidth and other resources.
One way to modernize a SCADA system is to invest in new IP capable SCADA equipment. That is, to replace each SCADA subsystem and associated master node with a new IP based SCADA subsystem and IP based master node. However, to do so can be a very costly, time consuming and service interrupting process.
In view of the foregoing it appears that an easy to manage and bandwidth efficient way to communicate traffic of a TDM based non-IP SCADA system over an IP/MPLS based infrastructure would be desirable.